Clamping and tensioning device



June 3, 1958 w. PECHY 2,837,025

CLAMPING AND TENSIONING DEVICE Filed May 8, 1956 2 Sheets-Sheet 1 WILLIAM PECHY WWW ATTORNEYS June 3, 1958 w, PEcHY 2,837,025

CLAMPING AND TENSIONING DEVICE Filed May 8, 1956 2 Sheets-Sheet 2 r INVENTOR.

- WILLIAM PECHY ATTORNEYS United States Patent fice CLAlVlPING AND TENSIONING DEVICE William Pechy, Belmar, N. 1., assignor to American Can Company, New York, N. Y., a corporation of New Jersey Application May 8, 1956, Serial No. 583,391

4 Claims. (Cl. 101-4151) The present invention relates to lithographing and printing presses and has particular reference to clamping devices for holding a printing plate or other flexible sheet in position on the outer face of the plate cylinder of the machine.

An object of the invention is the provision of clamping evices which are simple in construction and have few parts so as to obtain maximum efficiency with a minimum of maintenance.

Another object is the provision and location of such clamping devices which may be readily manipulated from the ends of the plate cylinder where ample room is available.

Another object is the provision of such clamping devices which permits of full encirclement of the plate cylinder by the plate so that only a negligible portion of the working surface of the plate cylinder is unused.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Figure 1 is a perspective view of a plate cylinder embodying the instant invention, the view showing a printing plate in position on the cylinder.

Fig. 2 is an enlarged longitudinal section taken substantially along a plane indicated by the lines 22 in Fig. 1;

Fig. 3 is an end view of the printing plate prepared for use on the cylinder shown in Pig. 1;

Fig. 4 is an enlarged fragmentary end elevation of the cylinder as viewed from the left in Fig. 2; and

Fig. 5 is a sectional view taken substantially along the line 5-5 in Fig. 2.

As a preferred or exemplary embodiment of the instant invention the drawings illustrate a clamping device (Fig. l) for holding a flexible printing plate A or other sheet in place on the outer cylindrical peripheral face 11 of a conventional plate cylinder 12 of a lithographing or printing press. The plate cylinder 12 is provided with trunnions 13 for mounting in the press.

The printing plate A preferably is made with a length greater than the circumference of the plate cylinder 12 so that it may completely surround the cylinder and still have marginal end portions or flanges B (Fig. 3) which are utilized to clamp the plate tightly around the cylinder without stretching it. In preparing the plate A for mounting on the cylinder 12, the marginal end portions B preferably are bent inwardly, substantially at right angles to the plate and with the portion of the plate between them being substantially equal in length to the circumference of the plate cylinder. The terminal edge portions of the inwardly bent end portions B may or may not as desired be formed with beads C for intermeshing cooperation in holding the ends of the plate in position as will be hereinafter explained. The plate A may be formed into tubular shape as shown in Fig. 3 for easy 2,837,025 Patented June 3, 1958 sliding over the end of the cylinder 12 or, if desired may be wrapped around the cylinder from its original fiat shape.

The clamping device 10 preferably is mounted in the cylinder 12 in such a manner as to engage and draw together the end portions or flanges B of plate A to hold the plate on the cylinder. For this puipose the clamping device includes a generally dovetail or trapezoid shape tightening bar or jaw 15 (Figs. 1, 3, 4 and 5) which preferably extends the full length of the plate cylinder 12 and which is loosely located in a correspondingly shaped larger clearance recess 16 formed in the outer cylindrical face 11 of the cylinder and extending longitudinally thereof, i. e. parallel with the axis of the cylinder.

The tightening bar or jaw 15 preferably is formed with a pair of opposed substantially parallel longitudinal faces constituting a long front face 18 (Fig. 4) and a short rear face 19 and a pair of angularly disposed top and bottom faces 21, 22 which flare outwardly from the rear face 19 to the front face 18. The front face 18 and the adjacent angular bottom face 22 at their point of convergence merge into a rounded edge head 23 which projects outwardly from the long front face 18 and which constitutes a pivot or a pivot edge for the tightening bar 15. This pivot edge or bead 23 loosely fits in a corresponding slightly larger concavity or socket 24 formed in the cylinder 12 at the base of the recess 16 and at the inner or lower terminal end of a support wall 26 defining one side of the recess 16. The support wall 26 is disposed at an angle to the long from face 18 of the tightening bar 15 with the outer edge of the wall 26 arranged in spaced relation to the outer edge of the front face 18 of the tightening bar as viewed in Fig. 4.

When the printing plate A is applied to the cylinder 12, the end portions or flanges B of the plate are inserted in the space between the long front face 18 of the tightening bar 15 and the support Wall 26 defining the recess 16 as shown in Fig. 4. The terminal edges or beads C of the end portions B of the plate are pushed down between the concavity 24 and the tightening bar edge head 23. If these terminal edges C are preformed in the plate they nest readily with one another within the concavity or socket 24. If they are straight, they will be bent to conform to the concavity 24 upon operation of the tightening bar 15 as will be described hereinafter.

The short rear face 19 of the tightening bar 15 pre ferably is provided with a pair of longitudinally spaced, recessed seats 28 (Figs. 2, 4 and 5) which engage against rounded faces 29 of a pair of wedge blocks 31 disposed in a longitudinal channel 32 formed in the cylinder 12 adjacent and communicating with the tightening bar recess 16. Opposite the rounded faces 29, the wedge locks 31 are formed with fiat inclined wedge face 34 which are inclined inwardly and in opposite directions toward the axis of the cylinder and outwardly toward the ends of the cylinder (Fig. 2), so that the wedge faces 34 extend in opposite relative directions on the two Wedge blocks.

The wedge faces 3-1 engage against and are backed up by separate corresponding wedge faces 35 on a pair of separate wedge bolts 36 disposed in the bottom of the channel 32. One or the outer end of each wedge bolt 36 extends out into a clearance bore 37 formed in the ends of the cylinder 12 so as to be readily accessible. These ends of the bolts 36 carry stop washers 38 and are each threaded to receive a nut 39. The washers 38 seat against the cylinder at the bottoms of the bores 37.

The nuts 39 are utilized to draw the printing plate A tight on the outer peripheral face 11 of the cylinder 12. This is effected by screwing the nuts 39 up on the wedge bolts 36. As the nuts are tightened, the wedge bolts 36 are drawn outwardly toward the opposite ends of the cylinder 12 and this efiects a relative movement between the wedge faces 35 of the bolts and the correspondingly tapered faces 34 on the wedge blocks 31 with the resuit that the wedge blocks are forced outwardly against the longitudinally aligned seats 29 of the tightening bar or jaw 15. This pressure on the bar 15 presses its longitudinal edge bead 23 tightly against the terminal edges or hollow beads C of the end portions Bof the printing plate A and thereby clamps the end portions B at their terminal edges C tightly together in the concavity 24. If the terminal edges C are initially straight to begin with, this tightening action bends them into the aforesaid hollow bead configuration to conform to the concavity 24 and thus holds them in place.

This outward pressure on the jaw 15 also pivots the jaw on its edge bead 23 in a direction toward the support wall 26 defining one side of the recess 16 and thereby tends to bring the outer edges of the plate end portions B together adjacent the circumferential outer face 11 of the cylinder 12 while their inner terminal edges C in the concavity 24 are clamped againstmovement by the jaw pivot head 23. The printing plate extending around the cylinder 12 is thus drawn taut and firm against the outer peripheral face 11 of the cylinder 12. Inward adjustment of the nuts 39 is continued until the plate A is drawn sufiiciently taut. Hence no locking devices are required to keep the jaw 15 in plate holding position.

When it is desired to remove the printing plate A it is only necessary to loosen the nuts 39 and push the wedge bolts 36 inwardly. This releases the jaw 15 from the end portions or terminalfianges B of the plate and permits ready removal of the plate from the cylinder.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing t description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. Means for clamping a flexible printing plate taut in a lithographing and printing press, comprising a plate cylinder having a longitudinal recess'therein for the reception of angularly inwardly bent end flanges of a printing plate carried on and surrounding said cylinder, said recess terminating at its inner end in an offset elongated rounded socket, an elongated jaw loosely contained in said recess and terminating in a rounded bead disposed in said socket for pivotal movement of the jaw in said recess, one side of said jaw being engageable with the inner surface of one of said inwardly bent plate end flanges, a longitudinal channel in said cylinder opening into said recess, wedging means longitudinally and laterally slidable in and relative to said channel and having a side thereof engageable with the adjacent side of said jaw, and means for efiecting longitudinal and lateral slid- 4 ing movement of said wedging means in said channel to pivotally rock said jaw in said recess on the jaw bead in said socket to force said printing plate flanges towards each other for drawing the plate taut on and around said cylinder.

2. Means for clamping a flexible printing plate taut in a lithographing and printing press, comprising a plate cylinder having a longitudinal recess therein for the reception of angularly inwardly bent end flanges of a printing plate carried on and surrounding said cylinder, said recess terminating at its inner end in an offset elongated rounded socket, an elongated jaw loosely contained in said recess and terminating in a rounded bead disposed in said socket for pivotal movement of the jaw in said recess, one side of said jaw being engageable with the inner surface of one of said inwardly bent plate end flanges, a longitudinal channel in said cylinder opening into said recess, a block member transversely slidable in said channel and having a side engageable with a side of said jaw, a wedge member longitudinally slidable in said channel and having a side engageable with the adjacent side of said block member, one of said inter engaging block and wedge member sides being longitudinally tapered, and means for effecting longitudinal sliding movement of said wedge member in said channel to slide said block member transversely thereof and thus pivotally rock said jaw in said recess to force said printing plate flanges towards each other for drawing the plate taut on and around said cylinder. 9

3. The clamping means as defined in claim 2, wherein a pair of said block members and a pair of said wedge members are disposed in longitudinally spaced side'by side abutting relation in said channel, and said wedge members comprise longitudinally tapered threaded bolts having fixed nuts thereon, whereby rotation of the nuts slides the bolts in opposite longitudinal directions and said block members laterally in the same direction in said channel for the purpose described.

4, Clamping means as defined in claim 2, wherein said rounded jaw bead is of less diameter than the diameter of said rounded socket and has a curvature conforming thereto for pivotal mounting of said jaw in the socket in clamped nesting engagement with similarly curved internesting terminal ends of said plate flanges.

References Cited in the file of this patent UNITED STATES PATENTS 1,620,685 Pannier Mar. 15, 1927 1,900,986 Gietz Mar. 14, 1933 2,056,991 Tomlin Oct. 13, 1936 2,639,668 Chase et al May 26, 1953 2,641,183 Boyajean June 9, 1953 2,768,579 Fies Oct. 30, 1956 FOREIGN PATENTS 617,936 Germany Aug. 30, 1935 641,173 Germany Ian. 23, 1937 

